CN102099981A

CN102099981A - Environmentally friendly power supply

Info

Publication number: CN102099981A
Application number: CN2009801168100A
Authority: CN
Inventors: D·马诺尔; P·莱本斯; R·范罗伊
Original assignee: Techtium Ltd
Current assignee: Techtium Ltd
Priority date: 2008-03-10
Filing date: 2009-03-10
Publication date: 2011-06-15
Also published as: US9954443B2; US20110051476A1; BRPI0909363A2; CA2718168A1; WO2009113062A3; US8446134B2; US20130250621A1; EP2266177A2; WO2009113062A2; JP2011514137A; KR20100134650A

Abstract

A power supply for converting AC to a regulated DC output current, utilizing two serial switched mode power supplies, the first providing an intermediate DC output voltage with only moderate ripple properties, this output being input to the second, which operates as a DC/DC converter to provide the desired output with low ripple and good regulation. The diode rectifier assembly has no reservoir/smoothing capacitor, or one of much smaller capacitance than in prior art power supplies. The large resulting rectifier output ripple is overcome by use of the two power supply units, at least the first having a smoothing capacitor at its output. A majority of the energy stored in this capacitor is utilized during each AC half cycle. Such power supplies also provide improved hold-up times. The power supply is also constructed to have low standby power consumption, by use of a double burst configuration.

Description

Environmentally friendly power supply

Technical field

The present invention relates to field of power supplies, the wall AC adapter of pegging graft especially, the power supply of wall grafting efficient that especially is designed to provide high and low stand-by power consumption.

Background technology

DC power supply by the AC mains powered may be the current modal power supply that uses, this power supply is used to the portable electron device power supply such as mobile phone, laptop computer, or to battery charge, for example known wall charger or adapter or the transducer of advancing.If " high efficiency " type, this power supply uses rectifier bridge usually, has capacitor output, be used to store and level and smooth purpose, DC/DC converter power supply for the switching mode type, generally be pulse-width modulation (PWM) power supply, this power supply also passes through the capacitor smoothing in its output, to produce the low voltage DC output of regulating.Although compare the efficient of this power supply with previously available linear stabilized power supply higher, but there is a kind of trend relevant further to raise the efficiency recently, especially they is being connected to mains supply but the not standby consumption of minimizing device when load provides electric current with environmental concern.

All need such power supply always, compare with the power supply of prior art, it further improves wall grafting efficient and reduces stand-by power consumption.

Open this paper that incorporates into by reference of each of the publication of mentioning in this joint of specification and other joints, each is all incorporated in full.

Summary of the invention

The present invention attempts to provide a kind of new power that AC power supplies is converted to the voltage stabilizing DC output current of expectation.The power subsystem of two series connection of this power utilization, first is the AC/DC converter, obtain the input of AC civil power and the middle DC output voltage that only has appropriateness even bad ripple character is provided, this output is imported into the second source unit, its as the DC/DC converter so that the desired output with low ripple and well-tuned to be provided.In whole the application, term " ripple " is interpreted as, also can advocate like this to be, refer to the voltage drop of the output that the crosspoint (cross-over point) of AC mains supply causes, wherein input voltage is along with intersect time and no-voltage position, thereby in this time period generally from alternate source, for example from the holding capacitor supply of current.Diode rectifier electric bridge or other rectifier stacks arrange with such prior art power supply difference and are that it does not use related storage/smmothing capacitor in its output reality.If use capacitor at the rectification output end place, it is worth significantly less than this prior art power supply, serves as the part of input RFI filter usually, rather than has smoothing function.Yet, the actual rectification output current that does not have storage/smoothing capacity to obtain to have big ripple of rectifier assembly output.Utilize the power supply of two series connection to overcome this big gained output ripple in power supply of the present invention, the capacitor that utilizes the output of first power supply is realized reducing this rectifier output ripple and any smoothing function of wishing.This capacitor at the first power output end place has been realized the storage/smoothing function in the circuit so, exactly.The AC/DC conversion electric power will can drop to originally when providing under the required voltage of rated output voltage at AC voltage and continue to the load supply of current, and this smoothing function is necessary.Power subsystem can be a switched-mode power supply, and these power supplys have good efficiency and control easily, although the circuit framework of explaining among the application generally is suitable for using the power subsystem or the voltage changer of any kind of.No matter use the term transform device in this application, and also can advocate like this, usually to represent the voltage transformation electric supply installation, be AC/DC or DC/DC.

Use two series electrical source modules to make it possible to use only to have that minimum levels is regulated and output has first power supply of higher ripple level (ripple level), obtain the adjusting of expectation level and low ripple at the output of second source then simultaneously.This combination makes any holding capacitor that uses in the power supply, no matter at the output of rectifier assembly still at the output of the first switched-mode power supply module, all have than the remarkable little value of prior art power supply, save the space thus and raise the efficiency.Any any this electric capacity that is installed in these two positions all has two kinds of character as characteristic of the present invention.At first, different with routine storage/smmothing capacitor (in order to keep low ripple level, allow it only to discharge the fraction of their stored energys in each cycle or half period), the capacitor of power supply of the present invention makes the major part that allows to utilize stored energy in them during each AC cycle or half period.Second, with the routine storage/smmothing capacitor that uses in the prior art small power supply (when replenishing for them, it only draws electric current from mains supply during the fraction in AC cycle) difference, the capacitor of power supply of the present invention makes and draw electric current during the major part in AC cycle.Force storage/smmothing capacitor and output voltage synchronously drawing electric current from mains supply on whole AC cycle or half period substantially although there is circuit of power factor correction to use active upconverter to control, routine storage/smmothing capacitor the work that such circuit general using is big, make them can not discharge the major part of their stored energys during each cycle or half period, these are different with capacitor of the present invention.The typical prior art power supply can use the about 30% of institute's holding capacitor energy, and as shown in hereinafter, and what the power configuration of describing among the application was typically used institute's holding capacitor energy surpasses 80%.

In the configuration of mentioning at using the holding capacitor in the described power supply of the disclosure, favourable layout is, rectifier output end only has minimum capacitive character and has (if any), generally be used for the RFI input filter, and allow the capacitor of output of the first switched-mode power supply module serve as the main storage/smmothing capacitor of power supply.

Another advantage of each power supply of the disclosure is, the intermediate voltage that the output of first switched-mode power supply is higher than specified output.The result, the electric current of this first switched-mode power supply supply is less than the electric current of the prior art unit supply of only using single switched-mode power supply, thereby reduced the resistance power consumption penalty like this, in ripple current, reduced power consumption penalty because need not to use the higher high value aluminum capacitor of its Leakage Current by group storage/smmothing capacitor, and in the loss of any series components that intermediate current is flowed through, be not always the case, as hereinafter will explaining.The DC/DC converter that use has low input/output voltage ratio allows this second source to have very high efficient as the second switch mode power, makes total power-efficient very high.

Use two series electrical source modules (wherein first output ratio device is at the higher intermediate voltage of the output place needs of second source module) to realize another useful configuration of power supply described in the disclosure, wherein two power module physics separately.This configuration has the following advantages.First power module can be incorporated in the plug that inserts in the AC wall plug, and the second source module can be to insert the load that will power or the module in the device.In the AC/DC of prior art wall charger power supply, generally all circuit are all incorporated in the plug that inserts in the wall plug into the whole rated current of carrying the lead of power output must the carry load device to need to load device.According to this separate power supplies configuration, because the more high voltage between two modules, the lead that first power module and the second source module of inserting in the load device at wall plug place linked together does not need to carry the electric current with prior art design same level.Like this, this root lead can be thinner than prior art design section, thereby it is wasting still less energy aspect resistance power consumption.In addition, it can have more flexibility, thereby it for example can be rolled on the reel in incorporating the wall outlet unit into.Also since the cushioning effect by the second switch mode power to the final burning voltage of device provisioning, the extra voltage on the thin connecting line falls, although bigger than conventional stube cable, also may not necessarily influence the output-voltage levels that offers device.

Another advantage of above-mentioned novel power supply structure is, can construct power supply, utilizes the dipulse configuration, makes it have low-down stand-by power consumption.According to this configuration, preferably monitor the voltage at the output two ends of each switched-mode power supply by the low voltage detector element, in case voltage level is elevated to more than the predetermined level of each power supply, expression lacks output loading, two power supplys are all closed fully, and the power consumption with whole power supplys is reduced to the power consumption that is only caused by the parts leakage thus.When the load current demand that the decline in monitored voltage is represented is lower than second predetermined value of each power supply, wake two parts power supplys up.Do not connect load but voltage detector because leakage of current still arrives when opening threshold value, power supply provides current impulse, and output voltage is brought up to cut-off level, powered-down once more.These pulse durations are very short, make total power consumption very low.

In addition, as hereinafter in detail as described in because the structure and the reason of circuit framework, can make the power factor of power supply of disclosure description better than the single-stage AC/DC power supply of prior art.Be used to this small-sized AC/DC power supply of electronic apparatus power supply generally not use power factor correction circuit.The improvement of the power factor of the present invention is not incorporate extra active power factor correction circuit into to realize.The improvement of this power factor also helps resources conservation.

Described another exemplary switched-mode power supply, wherein need not to use optical coupler just to realize the Control and Feedback that converter is imported, optical coupler is big and expensive component for the domestic power supply purposes.Described a kind of application, wherein, utilized the main transformer of pulse width modulated power supply so that return the feedback that provides from the voltage on the output capacitor to switched-mode power supply control, thereby at needs starting switch mode power when its sleep pattern is waken up.When switched-mode power supply is in its sleep pattern, do not use high frequency transformer, so it freely carries out this function.

More and more need to be used to the power supply of key device (generally being those devices except battery powered device) power supply should have the very big retention time now, make the c=device work between disconnected changing in the mains supply short-term.If the exemplary power supply described in the disclosure is suitable for use in the long retention time, the direct advantage of comparing with the prior art power supply becomes apparent.Because main energy storage capacitor is positioned at the output of first converter, substantially be independent of the variation of AC power supplies input voltage, they are charged to same nominal dc voltage all the time, the i.e. output voltage of first converter, thus though can the mains supply service conditions how all to select capacitor with energy that required accurate amount is provided to make (bridge) retention time up.So even mains supply will drop to its minimum value before breaking fully, the holding capacitor of these power supplys also will be all the time at essentially identical voltage level, promptly is recharged under the rated output voltage of first converter.The effect of first converter is that the stability of holding capacitor and A/C mains supply is kept apart, thereby provides to require to realize the ability of retention time than the remarkable undemanding capacitor of the power supply of prior art for these power supplys.

So, according to an exemplary embodiment of the present invention of being advocated, providing a kind of power supply that is used for AC power supplies is converted to DC output, this power supply comprises:

(i) be connected to AC power supplies and the rectifier assembly of rectified current is provided;

(ii) input rectifying electric current and first converter of a DC output current is provided;

(iii) import a DC output current and second converter of the 2nd DC output current is provided; And

(iv) be arranged at the output of first converter, be used to reduce at least one capacitor of the voltage drop of a DC output current during input AC power supplies zero passage,

Wherein, the electric capacity of described at least one capacitor makes during each half period of described AC power supplies the major part that discharges its stored energy.

This power supply can be so that first converter input rectifying output current during the major part at least of each half period of AC power supplies.In addition, the rectified current of the input end of first converter can have during input AC power supplies zero passage and accounts for the quite most voltage drop of its crest voltage.This voltage drop can be at least 50% of its peak voltage level.

In this power supply, first converter can advantageously provide the output voltage higher than second converter.This output voltage can be at least than second converter Senior Three/one.In any of these situations, the gained that flows in first converter reduces electric current and can cause the power consumption in it to reduce.

This power supply can advantageously make, described second converter than work, is imported described rectification output current and the efficient that obtains if make the efficient of described second converter be significantly higher than directly to it with fully little output and input voltage.

According to another exemplary power supply described here, the value of described at least one capacitor on the output of described first converter can so that, when described power supply provides the DC output current with its nominal level, the voltage drop of a described DC output current during input AC power supplies zero passage be at least described first converter output voltage 25%.Perhaps, the value of described at least one capacitor on the output of described first converter can so that, when described power supply provides the DC output current with its nominal level, the voltage drop of a described DC output current during input AC power supplies zero passage be at least described first converter output voltage 50%.

In addition, any above-mentioned power supply can be so that the described input that described first converter of rectified current provides during opening described power supply fully reduces impulse current, makes described power supply can save the needs of impact current protection.In addition, described first converter can be used to improve the power factor of described power supply to the utilance of rectification output current on the major part in each cycle of described AC power supplies.

Other example execution modes relate to aforesaid power supply, and wherein said rectifier assembly and described first converter are arranged in the module of separating with the second converter physics and by flexibly connecting cable and are connected thereto.In such power supply, this module can also comprise at least one capacitor.It can be the part that receives the wall outlet of AC power from wall plug easily, and second converter then can be the part of plug that is used to be connected to the load device of power supply, or it can be arranged within the electronic apparatus.This power supply can also comprise retractible spool, can be with the stube cable collection thereon when not using.

Another execution mode can relate to a kind of power supply, comprising:

(i) at least the first and second converters that are connected in series;

(ii) stride first at least one capacitor of the output connection of described first converter;

(iii) voltage detector component, it monitors the voltage on described first at least one capacitor, if the described voltage on described first at least one capacitor surpasses first predetermined level, make described first converter enter sleep pattern, if the described voltage on described first at least one capacitor drops to below second predetermined level, wake described first converter up from its sleep pattern;

(iv) stride second at least one capacitor of the output connection of described second converter; And

(v) voltage detector component, it monitors the voltage on described second at least one capacitor, if the described voltage on described second at least one capacitor surpasses the first preliminary election level, make described second converter enter sleep pattern, if the described voltage on described second at least one capacitor drops to below the second preliminary election level, wake described second converter up from its sleep pattern.

In this power supply, when not needing load current, described first converter can be waken up so that the voltage on described first at least one capacitor is brought up to described first predetermined level, and described second converter can be waken up the voltage on described second at least one capacitor is brought up to the described second preliminary election level.In addition, need not be from the load current of described power supply the time, it enters sleep pattern, except keep described converter to the response of wake-up signal required and parts reveal and loss, do not consume operating current substantially.

In addition, these power supplys can so that, described first and each of described second converter all be suitable for providing the electric current that only drops to the predetermined current lower limit, if and the electric current that wherein draws from described power supply drops to any second limit of the described predetermined current lower limit that is lower than described converter, in the described converter at least one enters sleep pattern, up to being waken up to be full of its at least one capacitor.In this case, can select any described predetermined current lower limit of described converter, make it only provide electric current with the level of keeping minimum predefine power-efficient.If the electric current that draws from described power supply drops to below described second limit, described at least one converter can provide greater than the pulse current of its predetermined current lower limit and between pulse can enter sleep pattern.

In more exemplary embodiment of these power supplys of mentioning at last, described rectifier assembly and described first converter can be arranged in the module of separating with the second converter physics and by stube cable and be connected thereto.In such power supply, this module can also comprise at least one capacitor.It can be the part that receives the wall outlet of AC power from wall plug easily, and second converter then can be the part of plug that is used to be connected to the load device of power supply, or it can be arranged within the electronic apparatus.This power supply can also comprise retractible spool, can be with the stube cable collection thereon when not using.

In addition, the alternate embodiment of describing among the application can relate to switched-mode power supply, comprising:

(i) be used to receive the input of DC electric current;

(ii) be used for producing the switching circuit of high-frequency AC electric current from described input DC electric current;

(iii) receive the high frequency transformer of the described high-frequency AC electric current in the elementary winding, described transformer has secondary winding, is used for exporting described high-frequency AC electric current with the voltage level of expectation;

(iv) be used for and become the rectification unit of DC output current through the described high-frequency AC current commutates of conversion; And

(the v) extra elementary winding of magnetic coupling to the described high frequency transformer of described secondary winding,

Wherein, the signal that is injected on the described secondary winding can bring out the signal of isolating and can be used for the controlled function in the described switched-mode power supply with described secondary winding electricity in described extra elementary winding.

Such switched-mode power supply can also comprise and is used to be connected to the AC mains supply, is used to provide the rectifier assembly of DC input current.In this case, the DC output current will be isolated with the AC mains supply, can advantageously need not optical coupler and realize this isolation.

According to another useful execution mode of the power supply of describing in the disclosure, a kind of power supply that is used for AC power supplies is converted to DC output can be arranged, described power supply comprises:

(iv) be arranged at the output of described first converter, be used to reduce at least one capacitor of the voltage drop of a described DC output current,

Wherein, the electric capacity of described at least one capacitor can be so that the voltage drop of a described DC output current be limited, makes described power supply that the predetermined portions of its power output was provided in the scheduled time after interrupting described AC power supplies.

In this power supply, the electric capacity of described at least one capacitor can be so that discharge the major part of its stored energy at described predetermined time period, and described power supply continues to provide the predetermined portions of its output in described predetermined time period.In addition, in this case, the permission that can be independent of AC power supplies voltage substantially changes and is independent of substantially uses by described first converter described at least one capacitor is charged to predetermined constant voltage for which AC power supplies voltage standard.

Description of drawings

By the detailed description that hereinafter provides in conjunction with the accompanying drawings, the present invention will obtain understanding and cognition more fully, in the accompanying drawing:

Fig. 1 shows the schematic circuit diagram of prior art wall power, and this power supply uses the level and smooth rectifier bridge of capacitor to be pulse-width modulation (PWM) DC/DC converter feed;

Fig. 2 shows the rectifier output of the prior art power supply of Fig. 1;

Fig. 3 shows the schematic circuit diagram according to the wall charger power supply of first preferred embodiment of the invention, and it has used the power subsystem of two tandem tap patterns;

Fig. 4 A shows the curve chart of the bridge output voltage of the power supply that is used for Fig. 3;

Fig. 4 B shows the output voltage curve of first switched-mode power supply of the embodiment of Fig. 3, and this power supply does not have output capacitor;

Fig. 4 C shows to first switched-mode power supply increases output capacitor and influence that the curve of Fig. 4 B is caused;

Fig. 5 schematically shows two level power supplies that can how to utilize dipulse configuration operation Fig. 3 embodiment, thereby reduces standby current greatly;

The schematic graph of the first switched-mode power supply unit output voltage of Fig. 5 embodiment that the dipulse that is to use Fig. 6 disposes;

The schematic graph of the second switch mode power unit output voltage of Fig. 5 embodiment that the dipulse that is to use Fig. 7 disposes;

Fig. 8 A schematically shows the much thin and/or much longer power line how Fig. 3 or 5 described two level power supplies can use load device from wall plug AC/DC power supply to its power supply to 8D;

Fig. 9 schematically shows the additional application of separate power supplies described in Fig. 8 A-8D, it can be advantageously used in the mancarried device such as mobile phone; And

Figure 10 is the schematic circuit diagram of no optical coupler execution mode of two level power supplies of Fig. 5.

Embodiment

Referring now to Fig. 1, show the schematic circuit diagram of prior art wall AC power supplies, this power supply uses capacitor level and smooth rectifier bridge 10 to be pulse-width modulation (PWM) DC/DC converter 12 feeds.At first can guide from the rectification output of electric bridge 10 and pass through the RFI filter, the RFI filter is π cross section filter normally, comprises the capacitor 15 of one or two inductor 13 and a pair of little value.This filter prevents that the inner noise radiation that produces turns back in the AC supply main in the power supply, requires to manage by regulating usually.In the embodiment shown in fig. 1, only show and singlely be used to store/capacitor 14 of level and smooth purpose, but be appreciated that also can use and independently store and smmothing capacitor with inductance between them or resistor.Storage/smmothing capacitor 14 is electrolytic capacitor normally.Because they are operated in high voltage, and since they need sufficiently high electric capacity good smooth level be provided, so they must be big parts.For for 5 watts, 5 volts power supplys of typical case of 220 volts of AC power supplies input operations, smmothing capacitor 14 is typically about 10 μ F to 25 μ F, and rated operational voltage is at least 350 volts.The capacitor of this 10 μ F has bigger physical size, general diameter 10mm * length 8mm.In addition, use the current-limiting components 16 of this large capacitor value requirement, so that when connecting, limit the impulse current that enters in the capacitor at input end use such as resistor.As normal conditions in this power supply, because adopt full-wave rectification, so every half period provides supplemental current for capacitor.This supplemental current betides in the big electric current than short pulse, because the purpose of storage/smmothing capacitor provides the as far as possible little output of ripple, the size and the cost of ripple and capacitor match.This means that input current can only charge to capacitor on the fraction of half period.Need be between the output of PWM and input the bridge joint feedback control loop, feedback control loop has optical coupler usually and isolates 19, so that the required control of output voltage is provided.

Output from rectifier bridge has been shown among Fig. 2.The ripple level depends on the value of used storage/smmothing capacitor, for described exemplary power supply, has the capacitor of 25 μ F, and ripple approximately is 30% of a DC output level.Capacitor is big more, and the ripple that PWM DC/DC converter need hold is just more little, and accurately power supply usually uses bigger capacitor and much lower ripple level.But, the good 5 volts pressure regulation of design are exported the PWM power supplys and can be tackled 50 volts or high input voltage ripple and not ging wrong more.Because because big smmothing capacitor 14, the input ripple that is input to pwm converter is lower, might use the electric capacity 18 of smaller value at the pressure regulation output of PWM power supply shown in Figure 1.Also show current impulse I among Fig. 2, this current impulse I is that every half period is drawn from rectifier assembly, as storing the usefulness of replenishing.

With reference now to Fig. 3,, shows the schematic circuit diagram of the exemplary novel wall charger power supply of type described in the disclosure.Generally this power supply is used to operate portable electron device or from the AC mains supply to battery charge.Charger be can construct to import the very AC voltage of wide region, between 85 and 265 volts,, and 1 ampere electric current, i.e. 5 watts output under 5 volts of pressure regulation dc voltages, exported usually with all general available resources of covering mains supply.

Be stressed that although in order to describe power work of the present disclosure has used 5 volts of 5 watts of power supplys in this section example, this is a common one exemplary embodiment fully, the present invention never is intended to be subject to the value that is used for this specific embodiment.

In addition, it is also understood that, although general use full-wave rectification in this power supply, thus current impulse takes place in per half period of AC power supplies, and the same consideration that designs about power supply also is applicable to halfwave rectifier.So, according to used rectification type, be intended in this application use term half period and cycle interchangeably, and be interpreted as claimed interchangeably like this.

In addition, although the power supply of these examples is described to utilize the power subsystem of pulse-width modulation (PWM), be appreciated that the controllable electric power unit that also can utilize any other type realizes them.

Charger is configured to have some favorable characteristics, and this is that current or imminent pressure regulation requirement or the market forces that turning round are desired.Especially charger design is become environmentally friendly, having does not waste the resource performance parameter.Below be the non-limiting tabulation of the charger of the present disclosure feature that should provide:

(i) be connected to mains supply but during not to the load power supply standby current very low.With common generally comparing up to the power consumption of 300mW in the prior art charger, exemplary 5 volts, 5 watts power supplys are designed to dissipate under holding state and are less than 30mW.

(ii) wall grafting efficient height.Compare with typical case's 70% efficient common in the prior art charger, Gou Zao typical power supply is designed to have at least 80% efficient as described in the present application, preferably up to 85%.In fact 85% efficient can cut down half with the power loss of duration of work.

(iii) high power factor.Compare with common 0.5 to 0.6 power factor in the prior art AC/DC charger, the exemplary power supply of the disclosure is designed to have at least 0.85 cosine φ.Occurring poor like this power factor in the prior-art devices generally is the big reservior capacitor that uses because of the output at the diode rectifier electric bridge, at the time durations of rectifier to reservior capacitor output supplemental current, big reservior capacitor draws big current impulse on the short time interval of each half period.Utilize the ACTIVE CONTROL feature that hereinafter will describe, and because draw the characteristic of electric current from mains supply on such major part of each AC half period (for full-wave rectification), the power supply of topological structure will be realized 0.9 power factor easily according to the present disclosure.

(iv) device volume is little.AC wall adapter charger according to the application is designed to have more small size than prior art charger, and this not only makes product more be accepted by market, and uses raw material still less when it is produced.

(v) good retention time characteristic.Can will become the long retention time can be provided according to exemplary electric source structure of the present disclosure, with the decline of reply mains supply, and compare with the prior art power supply of similar rated value utilize remarkable small size, still less the capacitor of cost and bigger reliability is realized this characteristic.This advantage be because with the prior art power supply in general may comparing, the utilance percentage of the power of storing in the capacitor is significantly bigger.

The difference of prior art power supply is described in the exemplary enforcement of the disclosure power supply shown in Fig. 3 and Fig. 1, and it has incorporated the PWM power supply of two series connection into, and a PWM power supply 32 is the 2nd PWM power supply 33 feeds.The first power supply PWM1 is configured to the DC/DC unit, with the relatively poor voltage of output stability, and can be than the high several times of output voltage of expectation.The PWM2 that is configured to the DC/DC converter obtains the good output of adjusting that this output and generation are in expectation voltage then.This layout provides some advantages, and these advantages are accumulated in can realize (if not whole) most of purpose mentioned above together.

At first, the power supply of Fig. 3 need not use storage/smmothing capacitor at rectifier output end.Exemplary power supply for 5 volts of the present disclosure, 5 watts, " holding capacitor " 30 (or " memory " and " smoothly " capacitor) that uses at the diode bridge output preferably only is about 0.1 μ F, and this is the fraction of typical case's 10 μ F value holding capacitors of using in the prior art power supply shown in Figure 1.The capacitor of this power supply has realized and the diverse function of the holding capacitor of prior art power supply that wherein its function is and the output of level and smooth electric bridge as much as possible proportionately of acceptable capacitor sizes.On the contrary, the one or more capacitors shown in the input end of the PWM1 in Fig. 3 serve as mandatory RFI assembly with suitable one or more inductors 31, are used to prevent that radiation is sent out back AC power supplies.Because they in the position of the porch of PWM1, here still are called them " input capacitor ".

Because the value of the input capacitor that uses in the exemplary power supply of Fig. 3 is little, thus impulse current in fact do not replenished in each half period, thus can eliminate the flow restricter 16 of Fig. 1, thus the waste energy that consumes in these parts saved.The 0.1 μ F input capacitor that uses is little more a lot of than the capacitor that uses in the prior art power supply on physical size.Except the advantage of physical size, so low capacitance make to use ceramic capacitor and non-polarized capacitor becomes feasiblely, can need electrolytic capacitor in the prior art power supply that uses a few μ F or higher smmothing capacitor.Ceramic capacitor has lower leakage and better overall high frequency performance than electrolytic capacitor, makes that it generally is favourable using them, and especially in the RFI filter assembly, and performance improves.

Yet, use the result of this small-sized input capacitor to be, the ripple level ratio prior art power supply in the rectifier assembly output is a lot of greatly.Fig. 4 A shows the curve chart of rectifier assembly output voltage of the exemplary power supply of Fig. 3, and from curve chart as can be seen, because input capacitor is so little, it almost completely is empty between the peak, does not work as the actual storage capacitor.If do not use input capacitor (under the situation that does not need the RFI filter) at all, bridge output voltage is in each half period, during each AC waveform zero passage, actually will drop to zero.Therefore power source features of the present invention can be that the first switched-mode power supply module PWM1 if not whole, draws electric current from rectifier assembly in the major part in AC cycle.

As the result of little input capacitor, the output voltage of electric bridge will change to the not peak output voltage of level and smooth rectifier assembly from the minimum value of tens volts or littler magnitude always.In example shown in Figure 3, for 250 volts AC wall voltage, this voltage is from about 60 volts to 360 volts peak value as can be seen, i.e. 300 volts or bigger scope.For the example shown in Fig. 3, structure PWM1 is to provide 15 volts DC output rated voltage.But, because input capacitor 30 is little, the output voltage of PWM1 also has big ripple, begins remarkable decline from output voltage during this part of each half period of AC zero cross near, shown in Fig. 4 B.In order to overcome this decline, this decline may deterioration be powered the work of device, increases capacitor 35 at the output of PWM1, the decline in the output characteristic shown in the blank map 4B then, thus obtain to have shown in Fig. 4 C the output of milder ripple.So this output capacitor 35 of PWM1 can be considered as serving as the holding capacitor of rectifier assembly, it is at the rotine positioning of rectifier output end, and in the back of the first switched-mode power supply module PWM1.Minimum ripple level depends on the size of used capacitor 35.If capacitor 35 is enough big, for described exemplary power supply, be approximately several thousand μ F, may just may obtain stable DC output up to 4,000 μ F, ripple is very little, is approximately 50mV, and this is the acceptable level to be used for mobile device.If use this large capacitor, just do not needed PWM2, so that satisfy the requirement of stable output.Capacitor about 10 μ F under the capacitor that is used for this size of working under low voltage is still significantly exported less than 350 volts peak values that are operated in diode bridge.So, compare with the prior art power supply of the similar rated value of type shown in Figure 1, even only use this example of a PWM (having the actual holding capacitor that moves to output from the input of PWM) also can reduce the size of power supply.

Yet, in order to improve the characteristic of power supply of the present invention more, refer again to Fig. 3, therefrom the output at capacitor 35 places is imported into the 2nd PWM 33 as can be seen, wherein carries out one-level DC/DC conversion, drops to 5 volts desired output voltage specifically.Because this PWM can use the DC output of PWM1 to import the adjusting that provides good as it, so it can reduce the value of capacitor 35 one to two orders of magnitude, is reduced to about 100 μ F usually for 15 volts, 5 watts exemplary outputs.So, have from 15 volts from the output of PWM1 and drop to usually even 6 volts ripple level.But, can easily tackle such wide input voltage range by PWM2 voltage.At the output of PWM2, as output filter, and provide sampled point for the low voltage detector of hereinafter describing in conjunction with the standby mode of PWM2 with small capacitor 37.The direct advantage of this preferred embodiment is, the output of the PWM1 capacitor sizes of specified 100 μ F, 16V usually is approximately diameter 7mm * height 4mm, significantly less than the capacitor of typical specified 4000 μ F, 5V, if only use a PWM, a kind of capacitor in back will be essential.Except the saving of incident cost and resource use, this provides with the prior art type of power of Fig. 1 as described power supply and has compared significant marketing advantage.

Extra advantage be because present embodiment more the capacity usage ratio of small capacitor 35 is higher.By expression formula E=V ²C/2 provides the ENERGY E of storing in the capacitor, and wherein V is the voltage on the capacitor C.In the prior art power supply that uses big storage/smmothing capacitor, the energy height of being stored, because the value of C is big, but because the ripple level must keep so little, so only there is very little part to be used for providing output during this part when the cycle is lower than condenser voltage from the input voltage of rectifier bridge in this stored energy by power supply.Provide the energy Δ E that is utilized by following formula:

ΔE＝(V ₁ ²-V ₂ ²)C/2，

Provide the ratio of actual energy utilance and theoretical maximum capacity usage ratio by following formula:

R _E＝(V ₁ ²-V ₂ ²)/V ₁ ²

V wherein ₁And V ₂Be peak value and the minimum voltage on the capacitor.Because the ripple V in the prior art power supply ₁-V ₂So little, so the ratio of the energy that utilizes is also little.According to the various examples of the application's power supply, the ripple voltage that their allow is very big, capacitor utilize energy quite big because V ₁And V ₂Between difference much bigger.As a result, the energy of capacitor 35 utilizes mark high a lot, and the energy of most of storage is used to fill up the low ebb in the PWM1 output.

Yet the extra cost of extra PWM module significantly surpasses because the power supply cost that capacitor C 35 sizes reduce to bring reduces in the power supply.As described below, owing to there is the additional benefit of using the 2nd PWM 33 to obtain, compensated this extra cost in the power supply described herein.

Power supply comprises two independently converter modules now, carries out the adjusting and the Current Regulation of output voltage in PWM2.PWM1 reality is only served as buffering DC power supply, and 15 volts of DC inputs of coarse adjustment are provided in PWM2, and the ripple level allows voltage to drop to 6 volts.Compare with single-stage power supply, self provide better gross efficiency this cutting apart because the AC/DC switched-mode power supply that in such as the prior art power supply, uses with big input/output voltage ratio and have little input/output voltage ratio as in existing between the PWM2 of DC/DC switched-mode power supply difference.AC/DC switched-mode power supply circuit with high voltage source input generally must have the topological structure that input and outlet side physics are separated, so circuit must float, without any publicly.The constrained that this topological structure applies the attainable efficient of this power supply.In addition, input/output voltage is bigger than very, drops to the 5V DC output of highly regulating from 360V AC peak value, and this may be difficult to realize with high efficiency.On the other hand, the DC/DC converter, for example PWM2 has much simple circuit topological structure, have and construct and little input/output voltage ratio publicly, thereby can realize very high efficient, as hereinafter further as described in.Although PWM1 also serves as the AC/DC power supply, be included in its function will importing the AC rectifier, thereby having floats when being configured to provide isolation between the input and output, significantly relaxed its condition of work, because it is more inessential that the output that requires is regulated, and input/output voltage is than the input/output voltage ratio of the only first power supply that is lower than prior art.Because the required adjusting level of PWM1 significantly reduces,, further saved component costs thus so the feedback circuit of PWM1 can be simpler than prior art power supply.

Use two series connection PWM unit to obtain improved efficiency and also have reason more specifically.Within each PWM,, generally there is input to switch and control circuit 55, high frequency transformer 56 and diode rectifier 57 as following shown in Figure 5.The pressure drop of about 0.6V is generally arranged at the diode rectifier two ends.According to the prior art example of Fig. 1, its PWM unit provides 5 volts output, and about 12% of 5 volts of output voltages are represented in the pressure drop of diode two ends 0.6V.On the other hand, in the embodiment of the invention shown in Figure 3,0.6 volt diode drop is only represented the about 4% of 15 volts of PWM1 output, makes that the power loss in the PWM unit has reduced 3 times.Express this comparison according to absolute loss, in 5 volts of prior aries, 5 watts of single PWM power supplys, 1 ampere rated current will be at diode two ends dissipation 600mW, and in 15 volts of same specified 5 watts power supplys, use described herein pair of converter architecture, the electric current of the 330mA 200mW that will only dissipate at the diode two ends has improved the efficient of a PWM unit thus.The power combination that this effect of the lower output current of PWM1 is saved with saving the impulse current limiter can realize the efficient of PWM1 90% together.Using the additional advantage of the higher DC output of PWM1 is the parasitic magnetic resistance that has reduced high frequency transformer 56, big about three times because secondary voltage compares when 5 volts of outputs directly are provided in a PWM power supply.This has saved the parts of this parasitic magneto resistance effect that is used to neutralize, and this also is favourable improving aspect the gross efficiency.

In addition, because PWM2 only under low pressure works now, improved rectification efficiency thus, thereby can realize efficient up to 95% so can use synchronous rectifier MOSFET to construct itself but not simple diode rectification.If because its lower rated current makes PWM1 can realize 90% efficient, the gross efficiency of novel power supply design so of the present disclosure will be about 90% * 95%=85%.In being to use this pair of PWM design can significantly improve the efficient of power supply.

In addition, for using little input capacitor, PWM1 also is used to improve the power factor of power supply.In the power supply of prior art, the size of holding capacitor makes diode bridge only need to be that capacitor replenishes amount seldom, for example from 300 to 360 volts, this input current pulse degradation of on the short part in cycle, drawing the power factor of installing.Little input capacitor allows the output of PWM1 significantly to descend, and drops to 6V from 15V in exemplary power supply of the present invention.In order to refill input capacitor, power supply in the much longer part in AC cycle (if do not use capacitor, then the AC cycle basic all on) in draw electric current from AC power supplies, thereby the use less current has been improved power factor thereby compare with the power supply of prior art in the longer time.

Because a lot of such power supplys, in particular for those of mobile phone purposes, spend its a lot of times in holding state, therefore compare with the environmental advantage that any minimizing that the standby current that draws from power supply can be realized brings, reducing of power loss between the operating period is very little usually, although himself is favourable to environment.In the power supply of prior art, in the example power supply as shown in FIG. 1, generally by guaranteeing to make that from the considerably less holding state that obtains the best of output capacitor 18 and drive circuit leakage thereof in fact PWM does not need to provide any electric current.But, it is movable that the PWM power supply remains, although its reality does not provide electric current, even reality is not drawn any electric current, its switch FET and other control systems are also being worked always, regulate output voltage.When dormancy, be the typical 300mW power consumption of these controlled function power supply of having compensated these prior aries.

With reference now to Fig. 5,, how it schematically show two level power supplies of application drawing 3 shown types, significantly reduces standby current thereby compare with the power supply of prior art, preferably reduces up to an order of magnitude.This system is by being called as the work of " dipulse " configuration.Detecting when not having load state, by closing two PWM fully, this power work, thus in PWM, do not use the control power supply.This power supply and different being shown in Figure 3 have increased low voltage detector (LVD) 51,52, are used to monitor the output voltage of each PWM level.Each LVD generally comprises the comparator with inner standard of precision voltage.Make that at output voltage when not pointing out any load situation, each LVD work is to close its PWM, up to producing next pulse.

At first see PWM1, with the overall work of awakening mode that power supply is shown, when PWM1 was in standby mode, it was fully closed, and controlled function must indicate it to wake up when needed.This is the function of LVD 52, hereinafter will describe its operation.Parts 53 are optical couplers, provide the isolation from the output of supply voltage at the input end of power supply.In the exemplary power supply described in Figure 10 below the alternative approach that this isolation is provided has been shown.Determine the signal that will wake up by the voltage on the monitoring PWM1 output capacitor 35.Control assembly in LVD 52 detects the moment that the voltage on the capacitor 35 that is caused by the load on the power supply descends, and the switching circuit 55 among their indication PWM1 is started working, and the PWM1 supply of current to be filling capacitor 35 again, and is the requirement power supply of load.

With reference now to PWM2,, its nominal is regulated and is output as 5 volts.The regulating characteristics of output of design PWM2 makes when not having load, or at the electric current that draws very hour, allows output voltage to increase very slightly, perhaps is increased to 5.2 volts.Low voltage detector 51 can be so that when its input voltage arrives 5.2 volts, and the signal of PWM2 is closed in its output fully, its supply voltage is disconnected connect, and makes PWM2 not draw any electric current substantially.LVD self draws low-down electric current, is typically about 1 microampere, makes its power consumption to ignore.Select LVD, make that when for example being 4.9 volts, LVD opens PWM2 once more, makes it improve output voltage once more in sequence of operations when its input voltage is slightly less than 5 volts of outputs of nominal of PWM2.Under non-loaded situation, when LVD will close PWM2 once more, the time that PWM2 may spend about 200 μ s brought the voltage up to 5.2V.As long as do not have load on the power supply, only owing to leakage reasons, output voltage descends very slowly, and it can spend about half second and drop to 4.9V from 5.2V.So the duty ratio of PWM power supply is approximately 200 * 10 ^-6/ 0.5, promptly only be 0.02%.Carry out pulse self under big electric current, even make short period when opening for it, its efficient also is high.Schematically show the output voltage of PWM2 in Fig. 6, wherein pulse manipulated effect is illustrated as the output voltage rising is got back to 5.2 volts.Obviously, if at the output of power supply load is arranged, the electric current that draws will stop output voltage to arrive 5.2V, and PWM will keep connection, according to load request under its normal current controlled mode to the load supply of current.So for PWM2, the total current drain from its input capacitor 35 to its output capacitor 37 under sleep pattern approximately only is the order of magnitude of 10 μ A.

PWM1 also works under the pulse mode configuration.LVD 52 has optical coupler 53 and is used for isolating, and the output of monitoring PWM1 also is designed to close PWM1 when its output voltage arrives 15V in this selected example.During non-loaded situation, output voltage is owing to the leakage at parts two ends descends, and selection LVD 52 circuit, be often used in connecting once more when voltage drops to low level PWM1, low level can be about 12V, and capacitor 35 is charged to its nominal voltage, 15V once more.As PWM2, thisly recharge the pulse operation time and also can be approximately 200 μ s.Be not to allow voltage attenuation to 6 volt, shown in Fig. 4 C, used higher connection voltage, for example 12V.Do making when during the situation of closing, needing load current like this,, abundant multipotency all should be arranged in capacitor 35 to start the power supply that directly links to each other no matter the time point that applies load in the curve chart of Fig. 7 how.If allow the voltage on the capacitor 35 to drop to 6 volts, and need electric current at that time point, PWM2 is the output burning voltage of the energy supply of storage expectation from capacitor 35 at once.Minimum voltage drop is restricted to high voltage, and for example 12V has guaranteed using the quick response of load.

Utilize the capacitor 35 of about 150 μ F, the energy of being stored makes the voltage attenuation on the capacitor allow past few second before another pulse of needs.This is long also to be to be caused by big differential ON/OFF voltage range at interval, means that the total current that PWM1 draws in its sleep pattern is very low.The result is that mainly the duration of being closed by PWM1 is determined total sleep pattern consumption, because pulse manipulated duty ratio is very short.In Fig. 7, schematically show the output voltage of PWM1, be reduced to 12 volts and just output voltage raise and get back to 15 volts in case wherein pulse manipulated effect is illustrated as it.

Be well known that usually, during far below its specified output services, its efficient generally can descend at power supply, no matter because the output current of their supplies how, the quiescent current that all has various circuit elements to use.Even the framework of various power supply examples of the present disclosure makes that power supply also continues with good efficiencies work when being operated in low output level.Can realize this point by following layout: Double-Pulse Operation not only is operated under the standby mode (does not have the electric current supply this moment) substantially, and is operated under the small-power, and wherein Gong Ying electric current is very low.This is that adjusting by " adjustment " power supply realizes.Under normal big current work state, power supply control guarantee to satisfy connect the electric current demand of load, thereby keep the stability of output voltage.Along with load reduces, power supply need also descend to the electric current of load supply.

Voltage-operated according to this pattern, the minimum current that PWM can supply is limited in some predetermined levels, and below the predetermined level, output current can not descend at these.Now, along with load continues to reduce, electric current can not drop under this predetermined level, and the unwanted excess current of load causes voltage to raise.The LVD one related with this PWM power supply detects this voltage and raises, and just closes PWM, thereby enters accurate holding state.Yet different with true holding state is (not drawing electric current from power supply substantially under true holding state), in this case, still draws low current, this electric current is left behind the output voltage of PWM power supply once more rapidly and is fallen, thus activating power once more, and withdraw from accurate holding state.So power supply enters and withdraws from its pulse working mode under little electric current.This mode of operation is the high-repetition-rate pulse mode of operation substantially, even guaranteed during little electric current, also efficient to be remained on acceptable level in supply, because power supply or to be in the suitable large-current electric with good efficiencies down flat, or close.In this case, and compare during the true holding state, pulse operation takes place with much higher speed substantially, and under true holding state, only leakage of current finally can cause the PWM power supply that current impulse is provided.

In a word, then this exemplary power supply can be operated under the some kinds of different modes:

1. standby or sleep pattern, this moment, two converters were all slept, and when the voltage of monitoring on one or more holding capacitors wakes PWM1 up and provides current impulse to replenish capacitor to survey.Usually under the full rate level of converter, supply pulse current to keep good work efficiency.

2. normal operation, medium or big electric current is low, during, the Current Control of PWM1 is guaranteed the requirement of output current matched load by in monitoring current and the output voltage at least one.Here do not use pulse mode work.

3. little current-mode, at this moment power work is in the pulse working mode type, and the pulse current that full level is provided guarantees to keep good efficiency thus with the matched load requirement.If the electric current slump in demand, the frequency of pulse diminishes so, but the current level within each pulse does not reduce.

By at two converters, the voltage on the output of PWM1 and the PWM2 monitoring holding capacitor is implemented control to these different modes.

PWM1 needs logical circuit so that guarantee, on the one hand, circuit all is ready to work at any time, allows to be no more than before power supply is provided the sub-fraction of millisecond, and on the other hand, circuit should sleep substantially fully when not using.

But, when power-off also is opened for the first time, for optical coupler, there is not voltage to can be used for making PWM1 can open oneself at all.Therefore, must provide logical circuit has voltage to can be used for correctly opening PWM1 so that guarantee optical coupler, thereby power supply is ready at any time work.Can not allow optical coupler to draw electric current being in sleep pattern following time, because that is with the performance of deterioration low current sleep pattern.So optical coupler is only worked when just drawing electric current, when not drawing electric current, close.

With reference now to Fig. 8 A, to 8D, it shows and how can advantageously use the duplicate supply topology of using two series electrical source modules mentioned above to provide with the wall plug power supply as the load device power supply, compare with the power supply of prior art, it has the more stube cable of small bore.Fig. 8 A shows this prior art AC/DC power supply 80 that is used to insert wall plug 81, and low-voltage cable 82 is connected to plug 83 with the output of power supply, and plug 83 is used for inserting the load device (not shown).Fig. 8 B shows the mechanical appearance according to the exemplary power supply 85 of the structure of circuit topology shown in above Fig. 3 and 5 now, and it has incorporated two pulse width modulated power supply modules into, is marked as PWM1 and PWM2.The cable 82 that this power supply 85 is connected to load device plug 83 is similar to the cable that uses in the prior art design shown in Fig. 8 A.

With reference now to Fig. 8 C,, it schematically shows another favorable structure of the power supply of disclosure description, and wherein two power modules are by physical isolation.First power module 86 that is labeled as PWM1 incorporated into be used for inserting in the plug of AC wall plug 81.The second source module 88 that is labeled as PWM2 is incorporated the plug that is used for being connected to load device into.The higher voltage of cable 87 bearing ratio load device required voltages that first power module 86 at wall outlet place and the second source module 88 of inserting load device are linked together, be typically the voltage under the 15V, the load device required voltage typically is each about 5 volts.Therefore, the stube cable 82 that wherein two voltage modules shown in the design of prior art shown in the current ratio Fig. 8 A in this cable and Fig. 8 B all are merged in the novel power supply design in the wall outlet 85 is lower, typically low three times.Therefore, the stube cable 87 of the separate power supplies block configuration shown in Fig. 8 C can have thinner cross section than the prior art of Fig. 8 A and Fig. 8 B.

This separate power supplies block configuration has some advantages:

(i) the more low current that flows to device plug 88 from wall outlet 86 is represented to compare with the power supply of prior art the stube cable 87 resistance consumption still less.Can more carefully and therefore have more flexible lead by use, or the more high efficiency of using the same cross-sectional lead to obtain realizes this purpose.Even use thinner lead, and diminish the voltage drop of becoming estranged, also can in second source module PWM2, compensate this voltage drop along cable.

(ii) two power modules can be constructed with little physical size.The first power module PWM1 can do fully for a short time owing to eliminated the general big smmothing capacitor that uses in the prior art design, it can be coupled to than in the big few plug of standard wall plug.Similarly, second source module PWM2 is the DC/DC converter, can do enough for a short time, and it is coupled to physically and the similar big plug of standard plug that is used for being connected to load device.

If (iii) use thinner stube cable 87, it will occupy more small size than prior art stube cable, shown in Fig. 8 D, can be collected in easily in the retractible spool 89, thereby can stash nattily when not using.Spool 89 can be incorporated within the wall outlet 86 self, realize compact especially layout.

With reference now to Fig. 9,, it schematically shows the additional application of the described separate power supplies of Fig. 8 A-8D, it can be advantageously used in the mancarried device such as mobile phone 93, mobile phone 93 has USB input 95, is used to the device power supply or is its internal cell charging.Wall outlet unit 91 is equivalent to the wall outlet unit 86 of Fig. 8 A-8D, be suitable for inserting in the AC mains supply, in this example mains supply be illustrated as between 80 and 265V between.It comprises rectifier bridge and DC/DC converter, is illustrated as PWM1 among the figure in front, and output storage/smmothing capacitor 92.This capacitor can be less electrolytic capacitor or tantalum capacitor, or even ceramic capacitor, because can tolerate high ripple at the output of converter, so allow its capacitance lower.Be similar to shown in Fig. 4 C, the figure that illustrates of this output has been shown in curve Figure 94.

The output cable of 91 beginnings is suitable for inserting the USB input of mobile phone 93 from the wall outlet unit.This input port is DC/DC converter 96 feeds, is realized by the PWM2 power subsystem in the earlier drawings among the application.Output from this DC/DC converter can be used for internal cell 97 charging of device or utilize 98 pairs of phones self power supplies of its controller.Carry out function then, have low ripple level from the output of DC/DC converter 96.This converter also provides the correct charging current characteristic that is used for the LI ion internal cell charging of phone.

For this cellular phone application, the output of wall outlet unit can drop to 5V up to 9V during DC input voltage zero passage.Such output is suitable for being input in the cellular USB input socket, and this socket typically can be accepted from the lower limit of USB power supply permission, and 4.4V is up to the DC of 10V input.So this execution mode can be provided as the wall adapter of the cell phone charging with USB input, this wall adapter is in light weight, efficient is high and size is little, also has other advantages of power supply structure mentioned above in the disclosure.

In power supply of the present disclosure, as shown in Figure 5, when PWM1 was in standby mode, it was closed fully, and controlled function must indicate it to wake up when needed, determined when needs by the voltage level on the output capacitor 35 of PWM1.In the moment that the voltage that detects on the capacitor 35 descends, for example when power supply applies load, the switching circuit 55 among the indication PWM1 is started working, and the PWM1 supply of current to be filling capacitor 35 again, and is the requirement power supply of load.Up to the present the power supply of Fig. 5 is described to use optical coupler 53, so that the supply voltage that the AC/DC converter input end at the some place of output of the low-tension supply of the user-isolated DC/DC converter that can touch and control AC/DC converter exists.In the prior art power supply of Fig. 1, also show such optical coupler.

Yet optical coupler is than expensive component, uses area valuable on the circuit board.So with reference now to Figure 10, it shows another exemplary power supply, wherein need not to use optical coupler just to realize Control and Feedback to the AC/DC converter.Utilize the main transformer of pulse width modulated power supply PWM1 so that provide the voltage from the output capacitor to return the feedback of PWM power supply control, so that when sleep pattern is waken it up, start PWM1 at needs.When PWM1 is in its sleep pattern, do not use high frequency transformer, so it freely carries out this function.

In Figure 10, show the discrete functional elements of converter PWM1, so that the operation of this specific implementations is shown.With power supply shown in Figure 5 public be that the power supply of Figure 10 comprises the DC/DC voltage changer of two series connection---PWM1 and PWM2.The pulse width modulated power supply difference of converter PWM1 and prior art is that except main elementary winding 102, high frequency transformer 100 also has extra elementary winding 101.Just be to use this extra winding to come emissioning controling signal, be used for waking the first converter PWM1 up, between first converter PWM1 that is directly connected to power input voltage and output stage, still provide isolation simultaneously from its sleep pattern.So this extra winding has been finished the optical coupler function of exemplary power supply in front and prior art power supply.

This execution mode is worked as follows.As in aforementioned embodiments, by the voltage on the control assembly 52 monitoring output capacitors 35.Control assembly 52 detect voltage on the output capacitor descended scheduled volume and need be in capacitor 35 moment of inflow current, perhaps just to the leakage that replenishes capacitor, perhaps, must wake the first converter PWM1 up so that this electric current flows in order to begin to the electric that is connected to output.Control assembly 52 is done like this by the grid supply pulse of the FET 103 that at first connects to rectifier diode 57 two ends.Closed FET of moment also is connected to capacitor 35 with Secondary winding of transformer 104, and current impulse is provided in secondary.This brings out equivalent current in the extra control winding 101 on transformer elementary.Form this pulse and be applied to the feedback input FB of the control circuit 55 of PWM1, it uses this signal to wake PWM1 up from its sleep pattern.Need unshowned added logic circuit among Figure 10, even so that when the control circuit of PWM1 is in standby mode, also can detect this enabling signal.When being waken up, PWM1 control circuit 55 to open MOSFET 106, makes a string electric current elementary winding 102 of can flowing through from output SW output control pulse, to fill capacitor 35 again.Normal power output run duration in rule uses MOSFET106, utilizes the electric current of the current sense input CS control process elementary 102 of control circuit 55, and its monitoring stream is through the primary current of resistor R.In addition, the normal power output run duration in rule can use the FB input that the voltage on the capacitor 35 is sampled, to be used for controlled function.

Thisly be furnished with two advantages.At first, provide isolation, do not need optical coupler by transformer 100.The second, be used for providing the same FET switch 103 of current impulse can also be used to carry out the synchronous rectification of transformer output current to secondary 104 of transformer.Compare with the voltage drop of forward biased diode 57 two ends 0.6V, the voltage drop at FET two ends can be hanged down 20mV when connecting.So, use synchronous rectification with Fig. 5 in the similar fashion described with respect to PWM2, saved almost whole power consumptions of rectifier diode 57 two ends, also improved the efficient of PWM1 greatly.

In Figure 10, the border of the first converter PWM1 that is represented by dashed boundary line is illustrated as and also comprises output capacitor electric voltage observation circuit 52 and MOSFET 103 and rectifier diode 57.It being understood that to comprise or do not comprise that parts are to determine arbitrarily as the part of PWM1, and do not mean that and limit this execution mode by any way.

In Figure 10, be independent of the control signal source, only apply the control input to PWM1.The result, although Figure 10 shows the control input function that the power supply that uses this extra elementary winding to describe type in the application who uses two series voltage converters provides isolation, but be appreciated that, this notion has wideer application in the prior art pulse width modulated power supply that comprises single PWM unit, should not think that this novel execution mode is intended to be limited to two converter topology structures mentioned above.When power supply is in sleep pattern and use control signal to wake it up, the advantageous particularly purposes aspect this of isolating transformer winding control has for example been described in the use under the configuration of pulse mode type.But, even the extra winding of possibility is also supplied the isolated controlling function signal when can be used in system's operate as normal, for example utilize the modulating frequency of removing from the switching mode frequency of power supply.

More and more need to be used to the power supply of key device (generally being those devices except battery powered device) power supply should have the very big retention time now.Be defined as importing that mains supply may cut off the power supply and power supply is still exported the time that is enough to drive for the electric current of its device that designs the retention time of power supply.In order in developed country, to use, need about 10 or retention time of 20ms usually, that is, and the complete cycle of half of complete cycle or AC mains supply.Than the under-developed area, supply of electric power is more unreliable, and the retention time in two or three cycles is common requirements, promptly up to 60ms.Be to utilize holding capacitor to realize the long like this retention time in the prior art power supply, holding capacitor is than original need much bigger of storage/smoothing function, and their use has guaranteed that power supply can provide its output from holding capacitor when the power supply input is lost.

Yet having its holding capacitor by the output at rectifier bridge in the prior art power supply provides the long retention time that the capacitor that is used for this function has been proposed very strict requirement.The rated voltage of this capacitor must be the peak-peak voltage of estimating when mains supply is in its maximum possible level, even simultaneously this capacitor volume must make them be in the specified output that can continue power supply when its minimum time point mains supply may level the time has a power failure at voltage.For example, consider to be used for the conventional power supply of nominal 220V AC mains supply.The voltage range of the necessary operate as normal of power supply is from 180V to 260V.For the maximum peak voltage that stands to estimate, the capacitor rated voltage is necessary for 400V.But for fully many memory spaces being arranged, provide input current in during electric capacity must keep in the time will only being charged to 190V voltage between the voltage decrement phase, to work on.Therefore these two parameters are that used capacitor has been stipulated high power capacity and high working voltage.The multiple power source situation of work is even more serious from 85V to 264V.Because need excess capacity to continue when under nominal input voltage, using in the work of the lower end of input voltage range, so this capacitor has only used the little percentage of stored energy in them.So, thereby when using under the specified 220V when having enough electric capacity greatly, only utilized the fraction of the energy of storing in the capacitor with the power supply of in some cycles, working in the 85V stored energy.

If exemplary power supply mentioned above in the disclosure is suitable for use in the long retention time, the direct advantage of comparing with the prior art power supply becomes apparent.Because main energy storage capacitor is positioned at the output of first converter, no matter the AC power supplies input voltage how, they are charged to same nominal dc voltage all the time, be the output voltage of PWM1, thus though can the mains supply service conditions how all to select capacitor with energy that required accurate amount is provided to make the retention time up.So even mains supply will drop to its minimum value before breaking fully, the holding capacitor of these power supplys also will be all the time at essentially identical voltage level, promptly is recharged under the rated output voltage of first converter.In other words, the effect of first converter is that the stability of holding capacitor and A/C mains supply is kept apart.In addition, the position of these holding capacitors is in than the expression of the lower voltage level point of mains supply level and can uses lower rated voltage capacitor.These two features all provide favourable cost, physical size and performance for the exemplary power supply that the disclosure is described.

Being used in being chosen in of storage capacitance in this bimodulus block power supply conceptive is identical with whether combining the retention time compensation.Holding capacitor is intended to make up input AC undertension and thinks that load provides the cycle of its electric current, the cycle when no matter being AC zero-crossing point period or AC power supplies complete failure.The standard of required electric capacity is different from mentioned above certainly, the decline of voltage during the zero crossing of only considering the AC cycle mentioned above.The standard that will use is now, during the maximum retention time of power supply design work, allows holding capacitor to discharge the major part of its energy, so that continue by the 2nd DC/DC converter operation load.This standard obviously need be used the capacitor bigger than the power supply that does not need the retention time, but still is to utilize this feature of most of energy of storing within the capacitor that this operation and the prior art power supply area that has capacitor at its input are separated.Difference is, during should using institute's stored energy most now be specified maintenance during, rather than half cycles cycle.Yet, should be understood that, the power supply that is equipped with the capacitor that the long retention time is provided no longer satisfies the best demand of the most efficient use memory capacity during week, and capacitor generally will have bigger value, thereby may no longer satisfy the most standard of using stored energy in the capacitor during each half period of AC power supplies.

The number of digital example is provided now so as the exemplary power supply of describing among illustration the application in the advantage aspect the retention time.

Provide the energy of storing in the capacitor: E=V by following formula ².C/2.Product by retention time and power output provides the energy that need store for the enough energy of supply in the given retention time in capacitor.

Select the rated voltage of retention time capacitor according to maximum input voltage, and select its electric capacity according to minimum input voltage.

Consider three examples:

1. the 220V prior art power supply (operating voltage 180-265V) of standard

2. general prior art power supply (85-265V)

3. the application has the power supply of two converter topologies

1.220V power supply:

The capacitor rated voltage is 400V, but capacitor only is charged to maximum prefetch phase crest voltage 370V.

Total stored energy is V ².C/2=370 ².C/2=68,450.C

For the energy of actual storage in the calculable capacitor percentage, carried out for 2 steps and calculate with respect to possible total stored energy:

(a)

Minimum peak input voltage V2=(180. √ 2-2)=253V

(voltage drop at the rectifier diode two ends deducts 2V)

Peak-peak input voltage V1=(265. √ 2)=370V

Therefore, do not consider because any voltage drop of causing of retention time is provided by following formula with respect to the energy of possible total stored energy in the minimum voltage storage:

(V2/V1) ²＝(253/370) ²＝47％。

So, under the AC of minimum permission line voltage, but capacitor only store its under the highest permission line voltage stored energy 47%.

(b)

Now, consider the voltage decline that the retention time causes, during the retention time, do not have input current to use, along with capacitor energy emptying flows into load, capacitor electrode drops.For the power supply of nominal 220V, thinking that still the maximum decline of the effective voltage available simultaneously of power supply is accepted as 80V.So the minimum capacitance device voltage can promptly drop to 173V from the 253V 80V that descends.

The ratio of the stored energy the when stored energy that the retention time is utilized before finishing when therefore, being provided the minimum capacitance device voltage and be 173V by following formula is 253V with respect to the minimum capacitance device voltage when the retention time begins:

(253 ²-153 ²)/253 ²＝53％。

In a word, for 220 volts of reference power supplies of AC/DC of prior art, only used available stored energy in the capacitor 47% 53%, promptly 25%.

When the general input voltage power supply that can use from 85V to 265V at nominal is carried out identical calculations, the result is, the retention time the duration, only used 6% of available stored energy in the capacitor to be transferred to load.

When carrying out these calculating at the power supply of type described in the disclosure, because the nominal voltage on the output capacitor is independent of the variation of AC power supplies voltage substantially, if do not consider the retention time, can think that capacitor stores 100% energy in used capacitor.

With respect to the decline of retention time, for the power supply of nominal 32V, thinking that still the maximum decline of the effective voltage available simultaneously of power supply is accepted as 19.5V.So the minimum capacitance device voltage can promptly drop to 12.5V from the 32V 19.5V that descends.

The ratio of the stored energy the when stored energy that the retention time is utilized before finishing when therefore, being provided the minimum capacitance device voltage and be 12.5V by following formula is 32V with respect to the minimum capacitance device voltage when the retention time begins:

(32 ²-12.5 ²)/32 ²＝85％。

In a word, used in the capacitor 85% available stored energy in this case, made such power supply more much higher than the energy storage efficiency of prior art power supply.

Also can calculate the difference of comparing with the conventional criteria power supply with the capacitor sizes of using in the illustration power supply of the present disclosure.The 40W power supply that with the retention time is 20ms is as prominent example, provided by the product of retention time and power output and realizes required stored energy of this retention time:

E=20 * 10 ^-3.40=0.8 joule.

Consider the inefficiency of power supply, holding capacitor should be designed to supply about 0.9 joule, so that power supply can provide the output that is enough to for its electric during the retention time.For the required holding capacitor of this 40W power supply example, computational chart is understood following characteristic:

(i) standard 220V prior art power supply:

68 μ F, the 400V rated value.Size is typically 20mm diameter * 35m length

(ii) general 85 arrive 264V prior art power supply:

270 μ F, the 400V rated value.Size is typically 30mm diameter * 40m length

(iii) according to the multiple power source of the application structure:

2200 μ F, the 35V rated value.Size typical case 16mm diameter * 25m length.

As can be seen, use the novel electric source topology described in the disclosure can utilize the yardstick significantly littler, lower operating voltage and therefore higher reliability and more low-costly provide the required retention time than prior art power supply.

Person of skill in the art will appreciate that, the invention is not restricted to the content that above specifically illustrates and describe.On the contrary, scope of the present invention comprises various combination of features mentioned above and sub-portfolio, and those skilled in the art are reading above afterwards thinkable its not in the prior art variation and the modification of describing.

Claims

1. one kind is used for converting AC power supplies to power supply that DC exports, and described power supply comprises:

Rectifier assembly is connected to described AC power supplies and rectified current is provided;

First converter is imported described rectified current and a DC output current is provided;

Second converter is imported a described DC output current and the 2nd DC output current is provided; And

At least one capacitor is arranged at the output of described first converter and is used to reduce the voltage drop of a described DC output current during described input AC power supplies zero passage,

2. power supply according to claim 1, wherein, described first converter is imported described rectification output current during the major part at least of each half period of described AC power supplies.

3. according to each the described power supply in claim 1 and 2, wherein, the described rectified current of the input end of described first converter has during input AC power supplies zero passage and accounts for the quite most voltage drop of its crest voltage.

4. according to each the described power supply in claim 1 and 2, wherein, the described rectified current of the input end of described first converter has the voltage drop that accounts for its peak voltage level at least 50% during input AC power supplies zero passage.

5. according to each the described power supply in the aforementioned claim, wherein, described first converter provides the output voltage that is higher than described second converter.

6. power supply according to claim 5, wherein, described first converter provides than described second converter Senior Three/one output voltage at least.

7. according to each the described power supply in claim 5 and 6, wherein, the gained that flows in described first converter reduces electric current and has reduced its power dissipation.

8. according to each the described power supply in claim 5 and 6, wherein, described second converter than work, makes the efficient of described second converter be significantly higher than directly the efficient that obtains with fully little output and input voltage when it imports described rectification output current.

9. according to each the described power supply in the aforementioned claim, wherein, the value of described at least one capacitor on the output of described first converter makes, when described power supply provides the DC output current with its nominal level, the voltage drop of a described DC output current during input AC power supplies zero passage be at least described first converter output voltage 25%.

10. according to each the described power supply in the aforementioned claim, wherein, the value of described at least one capacitor on the output of described first converter makes, when described power supply provides the DC output current with its nominal level, the voltage drop of a described DC output current during input AC power supplies zero passage be at least described first converter output voltage 50%.

11. according to each the described power supply in the aforementioned claim; wherein; the described input that described first converter of rectified current provides during opening described power supply fully reduces impulse current, makes described power supply can save the needs of impact current protection.

12. according to each the described power supply in the aforementioned claim, wherein, described first converter is used to improve the power factor of described power supply to the utilization of rectification output current on the major part in each cycle of described AC power supplies.

13. according to each the described power supply in the aforementioned claim, wherein, described rectifier assembly and described first converter are arranged in the module of separating with the described second converter physics and by flexibly connecting cable and are connected thereto.

14. power supply according to claim 13, wherein, described module also comprises described at least one capacitor.

15. according to each the described power supply in the claim 13 to 14, wherein, described module is the part that receives the wall outlet of AC power from wall plug, described second converter is the part of plug that is used to be connected to the load device of described power supply.

16. according to each the described power supply in the claim 13 to 14, wherein, described second converter is arranged within the electronic apparatus.

17. each the described power supply according in the claim 13 to 16 also comprises retractible spool, when not using, described stube cable collection thereon.

18. a power supply comprises:

At least the first and second converters that are connected in series;

Stride first at least one capacitor of the output connection of described first converter;

Voltage detector component, monitor the voltage on described first at least one capacitor, if the described voltage on described first at least one capacitor surpasses first predetermined level, make described first converter enter sleep pattern, if the described voltage on described first at least one capacitor drops to below second predetermined level, wake described first converter up from its sleep pattern;

Stride second at least one capacitor of the output connection of described second converter; And

Voltage detector component, monitor the voltage on described second at least one capacitor, if the described voltage on described second at least one capacitor surpasses the first preliminary election level, make described second converter enter sleep pattern, if the described voltage on described second at least one capacitor drops to below the second preliminary election level, wake described second converter up from its sleep pattern.

19. power supply according to claim 18, wherein, need not be the time from the load current of described first converter, described first converter can be waken up so that the voltage on described first at least one capacitor is brought up to described first predetermined level, and described second converter can be waken up the voltage on described second at least one capacitor is brought up to the described first preliminary election level.

20. according to each the described power supply in claim 18 and 19, wherein, need not be the time from the load current of described power supply, described power supply enters sleep pattern, except keep described converter to the response of wake-up signal required and parts reveal and loss, do not consume operating current substantially.

21. power supply according to claim 18, wherein, described first and described second converter in each all be suitable for providing the electric current that only drops to the predetermined current lower limit, if and the electric current that wherein draws from described power supply drops to any second limit of the described predetermined current lower limit that is lower than described converter, in the described converter at least one enters sleep pattern, up to being waken up to be full of its at least one capacitor.

22. power supply according to claim 21 wherein, is selected any described predetermined current lower limit of described converter, makes it only provide electric current with the level of keeping minimum predefine power-efficient.

23. according to each the described power supply in claim 21 and 22, wherein, if the electric current that draws from described power supply drops to below described second limit, described at least one converter provides greater than the pulse current of its predetermined current lower limit and enter sleep pattern between pulse.

24. according to each the described power supply in the claim 18 to 23, wherein, described first converter separates with the described second converter physics, described converter is connected by stube cable.

25. power supply according to claim 24, wherein, described first converter is the part that receives the wall outlet of AC power from wall plug, and described second converter is the part of plug that is used to be connected to the load device of described power supply.

26. each the described power supply according in claim 24 and 25 also comprises retractible spool, when not using, described stube cable collection thereon.

27. a switched-mode power supply comprises:

Be used to receive the input of DC electric current;

Be used for producing the switching circuit of high-frequency AC electric current from described input DC electric current;

Receive the high frequency transformer of the described high-frequency AC electric current in the elementary winding, described transformer has secondary winding, is used for exporting described high-frequency AC electric current with the voltage level of expectation;

Be used for to become the rectification unit of DC output current through the described high-frequency AC current commutates of conversion; And

The extra elementary winding of magnetic coupling to the described high frequency transformer of described secondary winding,

Wherein, the signal that is injected on the described secondary winding brings out the signal of isolating and can be used for the controlled function in the described switched-mode power supply with described secondary winding electricity in described extra elementary winding.

28. switched-mode power supply according to claim 30 also comprises being used to be connected to the AC mains supply, is used to provide the rectifier assembly of described DC input current.

29. switched-mode power supply according to claim 28, wherein, described DC output current and described AC mains supply are isolated.

30. switched-mode power supply according to claim 28, wherein, described DC output current and described AC mains supply are isolated and be need not optical coupler.

31. a power supply that is used for AC power supplies is converted to DC output, described power supply comprises:

At least one capacitor is arranged at the output of described first converter and is used to reduce the voltage drop of a described DC output current,

Wherein, the electric capacity of described at least one capacitor makes that the described voltage drop in the described DC output current is limited, makes described power supply continue predetermined amount of time after interrupting described AC power supplies the intended power output level is provided.

32. power supply according to claim 31, wherein, the electric capacity of described at least one capacitor makes the major part that discharges its stored energy at described predetermined amount of time, and described power supply continues to provide the predetermined portions of its output in described predetermined amount of time.

33. according to each the described power supply in claim 31 and 32, wherein, the permission variation that is independent of AC power supplies voltage substantially is charged to predetermined constant voltage by described first converter with described at least one capacitor.

34. power supply according to claim 33 wherein, is independent of substantially and uses which AC power supplies voltage standard by described first converter described at least one capacitor to be charged to predetermined constant voltage.